In the production of articles from cellulose, cellulose may have to be dissolved to form a solution thereof. The dissolution of cellulose can be effected with a solvent which is a mixture of N-methyl-morpholine-N-oxide (hereinafter NMMO) and water. The dissolved cellulose can be extruded or spun and thereafter precipitated with the aid of water to yield a film, thread or filament or a shaped body or material having a cellulose base (see Austrian Patent 376 986).
To dissolve the cellulose, a mixture of cellulose, water and NMMO is agitated under vacuum and heated water is drawn off until the cellulose has been completely solubilized. The resulting water vapor is condensed in a condenser. As a result of the thermal action on the NMMO, dependent upon the temperature and the duration of the thermal loading, the cellulose concentration and the quality of NMMO used, N-methylmorpholine and morpholine can be formed. Both of these substances are volatile and are condensed with the water vapor in the head product (so-called vapor condensate). The latter may also include spattering or spray from the original NMMO solution, and a delay in boiling can also entrain NMMO into the vapor condensate.
The vapor condensate which is thus obtained can include a maximum of 5% N-methylmorpholine, morpholine and NMMO. The vapor condensate is an environmental pollutant and cannot be discharged without treatment. It also represents a loss of valuable chemicals with respect to the morpholine, N-methylmorpholine and NMMO.
It is, therefore, necessary to treat the vapor condensate to remove the N-methylmorpholine, morpholine and NMMO therefrom or, conversely, to recover them from the water of the vapor condensate. This cannot be done easily or at sufficiently low cost by distillation or rectification. A separation utilizing cation exchange resins can be used but, after the ion exchange material has been loaded, it must be regenerated with inorganic or organic acids. This entails a number of drawbacks.
The use of inorganic or organic acids for regeneration gives rise to significant waste water loading with the regenerating acids and any rinsing liquids which may be required. The regeneration with organic acids permits a recirculation of the regenerating acid and complete disposal by combustion. However, the removed amines cannot be recycled or reprocessed since they are recovered as salts which pose problems in processing and, particularly, results in chemical losses. The capital cost and operating cost of apparatus of the ion exchange process are relatively high.